Introduction

JavaScript arrays offer many advanced methods to manipulate elements, find values, and transform arrays efficiently. 🧩

1️⃣ findLast()

Returns the last element that satisfies a condition.

const arr = [1, 2, 3, 4, 5];
console.log(arr.findLast(x => x % 2 === 0)); // 4

2️⃣ findLastIndex()

Returns the index of the last element that satisfies a condition.

const arr = [1, 2, 3, 4, 5];
console.log(arr.findLastIndex(x => x % 2 === 0)); // 3

3️⃣ at()

Access elements using positive or negative index.

const arr = [10, 20, 30];
console.log(arr.at(-1)); // 30

4️⃣ copyWithin()

Copies a portion of the array to another location in the same array.

const arr = [1,2,3,4,5];
arr.copyWithin(0,3);
console.log(arr); // [4,5,3,4,5]

5️⃣ fill()

Fills elements of an array with a static value.

const arr = [1,2,3];
arr.fill(0);
console.log(arr); // [0,0,0]

6️⃣ reverse()

Reverses the array in place.

const arr = [1,2,3];
arr.reverse();
console.log(arr); // [3,2,1]

7️⃣ flatMap()

Maps each element and flattens the result into a new array.

const arr = [1,2,3];
const result = arr.flatMap(x => [x, x*2]);
console.log(result); // [1,2,2,4,3,6]

8️⃣ every()

Checks if all elements satisfy a condition.

const arr = [2,4,6];
console.log(arr.every(x => x % 2 === 0)); // true

9️⃣ some()

Checks if at least one element satisfies a condition.

const arr = [1,3,4];
console.log(arr.some(x => x % 2 === 0)); // true